1. Field of the Invention
The present invention relates to a three-dimensional data input apparatus for inputting three-dimensional data by measuring an object to be measured.
2. Description of the Related Art
As apparatuses for inputting three-dimensional data of an object without making contact therewith, three-dimensional data input apparatuses employing a light section method, an optical time-of-flight method and a stereo method have conventionally been known.
By repeating a fixed point observation as described below by use of a three-dimensional data input apparatus as mentioned above, changes in configuration and external appearance of an object whose configuration and external appearance change with time, such as a plant in a flowerpot or a building under construction, can be captured.
That is, the object is measured by use of a three-dimensional data input apparatus, thereby obtaining first three-dimensional data. After a lapse of a predetermined time or period, the same object is measured from the same position, thereby obtaining second three-dimensional data. By comparing the first and the second three-dimensional data, the amount of change with time is obtained. Thereafter, three-dimensional data is obtained a plurality of times in a similar manner, and by comparing the three-dimensional data obtained at the times, the amount or the manner of change with time is obtained.
When the object is one that can be moved or tilted like a plant in a flowerpot, the relative position relationship between the object and the three-dimensional input apparatus can be easily changed. Therefore, it is unnecessary to take the three-dimensional input apparatus out to the place where the object is situated, but by bringing the object in the room where the three-dimensional input apparatus is placed, measurement can be made under excellent conditions. When the object is a building or a landform, however, the object cannot be moved. Therefore, it is necessary to place the three-dimensional input apparatus in the same position as the position where the last measurement was performed and measure the object from the position in the same direction as that in which the last measurement was performed.
As an apparatus for inputting three-dimensional data of an object such as a building or a landform, an apparatus described in Japanese Laid-open Patent Application H10-132562 has been proposed.
This apparatus measures the distances to target points of the object by the stereo method, and is provided with measuring devices such as a GPS (global positioning system) receiver, a magnetic sensor and a gyrocompass. Based on the measurement position of the apparatus detected by the GPS receiver, the azimuth data of the target points detected by the magnetic sensor and the inclination data detected by the gyrocompass, the distances to the target points and the altitudes of the target points are calculated on the principle of triangulation. The measurement data detected by the measuring devices and the calculated three-dimensional data such as the distances and the altitudes are recorded in a recorder, or displayed on a display together with a two-dimensional image of the object in response to an operation by the user.
To perform a fixed point observation by use of the three-dimensional data input apparatus as described above, it is necessary to perform a comparison between the present and past data with respect to the three-dimensional data, the measurement position data and the measurement direction data obtained through the measurements.
However, in the apparatus described in the above-mentioned patent application, since the data are merely displayed on a display, it is not easy to compare them. That is, for example, it is not easy to extract the three-dimensional data obtained through a measurement performed under the same condition as the present measurement, from a multiplicity of data measured and recorded in the past. Moreover, it is not easy to extract the measurement position data and the measurement direction data obtained when the measurement was performed under a similar condition to the present measurement, from a multiplicity of data measured and recorded in the past.